The entire raw NCAs are encrypted.

The only known area which is not encrypted in the raw NCA is the logo section, when the NCA includes that section. Everything else documented on this page is for the plaintext version of that data.

Header

Offset	Size	Description
0x0	0x100	RSA-2048 signature over the 0x200-bytes starting at offset 0x200 using fixed key.
0x100	0x100	RSA-2048 signature over the 0x200-bytes starting at offset 0x200 using key from NPDM, or zeroes if not a program.
0x200	0x4	Magicnum "NCA3"
0x204	0x1	?
0x205	0x1	Type value?
0x206	0x1	Crypto flags? Normally 0. With 3.0.0+ ncatype1(not used for ncatype0, unknown for others) content this is 2: new keydata is used for this content, this field seems to control that.
0x207	0x1	Key index
0x208	0x8	Size of the entire NCA.
0x210	0x8	titleID
0x230	0x10	Rights ID (Ticket)
0x240	0x10*0x4(0x40)	Table for each section, see below.
0x280	0x20*0x4(0x80)	Table of SHA256 hashes, over each 0x200-byte Section Header Block.
0x300	0x10*0x4(0x40)	Key area

The header is 0x400-bytes, at NCA+0.

Section Table Entry

Offset	Size	Description
0x0	0x4	Media offset
0x4	0x4	Media end-offset
0x8	0x4	Unknown
0xC	0x4	Unknown

Entry size is 0x10-bytes.

Media offset is absoluteoffset/{mediasize}, where mediasize is hard-coded to 0x200.

Section Header Block

Offset	Size	Description
0x0	0x1	?
0x1	0x1	?
0x2	0x1	?
0x3	0x1	?
0x4	0x1	Crypto type. 0 and >4 are invalid. 1 = none(plaintext from raw NCA). 2 = other crypto. 3 = regular crypto. 4 = unknown.
0x5	0x1	Padding?
0x8		FS-specific superblock.

The Section Header Block for each section is at absoluteoffset+0x400+(sectionid*0x200), where sectionid corresponds to the index used with the entry/hash tables.

The total size is 0x200-bytes.

PFS0 superblock

Offset	Size	Description
0x8	0x20	SHA256 hash over the hash-table at section-start+0 with the below hash-table size.
0x28	0x4	Block size in bytes.
0x2C	0x4	?
0x38	0x8?	Size of hash-table.
0x40	0x8?	Offset relative to section-start where the PFS0 header is located.
0x48	0x8	Actual byte-size of the PFS0 filesystem relative to the PFS0 header.
0x50	0xF4	Normally zeros.
0x144	?	0x1?
0x148	0xB8	Normally zeros.

This documents the structure of Section Header Block +0 for PFS0.

RomFS superblock

Offset	Size	Description
0x8		IVFC header

This documents the structure of Section Header Block +0 for RomFS.

Logo section

This is a PFS0. See here for the mounted-FS logo contents.

ExeFS section

This is a PFS0.

See here for mounted-FS ExeFS contents.

PFS0

Offset	Size	Description
0x0	X	Table of SHA256 hashes.
X	Y	Zeros for alignment to {alignment size}.
X+Y		Start of the PFS0 header.

This is the FS which has magicnum "PFS0" at header+0.

The hash table is hashes for every {Block size from superblock} starting at the PFS0 header. The size used for the last hash is {PFS0 filesystem size from superblock} - offset_relativeto_header.